Dataset Information

MRX8, the conserved mitochondrial YihA GTPase family member, is required for de novo Cox1 synthesis at suboptimal temperatures in Saccharomyces cerevisiae.

ABSTRACT: The synthesis of Cox1, the conserved catalytic-core subunit of Complex IV, a multisubunit machinery of the mitochondrial oxidative phosphorylation (OXPHOS) system under environmental stress, has not been sufficiently addressed. In this study, we show that the putative YihA superfamily GTPase, Mrx8, is a bona fide mitochondrial protein required for Cox1 translation initiation and elongation during suboptimal growth condition at 16°C. Mrx8 was found in a complex with mitochondrial ribosomes, consistent with a role in protein synthesis. Cells expressing mutant Mrx8 predicted to be defective in guanine nucleotide binding and hydrolysis were compromised for robust cellular respiration. We show that the requirement of Pet309 and Mss51 for cellular respiration is not bypassed by overexpression of Mrx8 and vice versa. Consistently the ribosomal association of Mss51 is independent of Mrx8. Significantly, we find that GTPBP8, the human orthologue, complements the loss of cellular respiration in Δmrx8 cells and GTPBP8 localizes to the mitochondria in mammalian cells. This strongly suggests a universal role of the MRX8 family of proteins in regulating mitochondrial function.

SUBMITTER: Verma Y

PROVIDER: S-EPMC8693954 | biostudies-literature | 2021 Nov

REPOSITORIES: biostudies-literature

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<i>MRX8</i>, the conserved mitochondrial YihA GTPase family member, is required for de novo Cox1 synthesis at suboptimal temperatures in <i>Saccharomyces cerevisiae</i>.

Verma Yash Y Mehra Upasana U Pandey Dharmendra Kumar DK Kar Joy J Pérez-Martinez Xochitl X Jana Siddhartha S SS Datta Kaustuv K

Molecular biology of the cell 20210825 21

The synthesis of Cox1, the conserved catalytic-core subunit of Complex IV, a multisubunit machinery of the mitochondrial oxidative phosphorylation (OXPHOS) system under environmental stress, has not been sufficiently addressed. In this study, we show that the putative YihA superfamily GTPase, Mrx8, is a bona fide mitochondrial protein required for Cox1 translation initiation and elongation during suboptimal growth condition at 16°C. Mrx8 was found in a complex with mitochondrial ribosomes, consi ...[more]

PMID: 34432493

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Project description:BACKGROUND:(+)-Nootkatone is a highly valued sesquiterpenoid compound, exhibiting a typical grapefruit aroma and various desired biological activities for use as aromatics and pharmaceuticals. The high commercial demand of (+)-nootkatone is predominately met by chemical synthesis, which entails the use of environmentally harmful reagents. Efficient synthesis of (+)-nootkatone via biotechnological approaches is thus urgently needed to satisfy its industrial demand. However, there are only a limited number of studies that report the de novo synthesis of (+)-nootkatone from simple carbon sources in microbial cell factories, and with relatively low yield. RESULTS:As the direct precursor of (+)-nootkatone biosynthesis, (+)-valencene was first produced in large quantities in Saccharomyces cerevisiae by overexpressing (+)-valencene synthase CnVS of Callitropsis nootkatensis in combination with various mevalonate pathway (MVA) engineering strategies, including the expression of CnVS and farnesyl diphosphate synthase (ERG20) as a fused protein, overexpression of a truncated form of the rate-limiting enzyme 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase (tHMG1), and downregulating the squalene synthase enzyme (ERG9). These approaches altogether brought the production of (+)-valencene to 217.95 mg/L. Secondly, we addressed the (+)-valencene oxidation by overexpressing the Hyoscyamus muticus premnaspirodiene oxygenase (HPO) variant (V482I/A484I) and cytochrome P450 reductase (ATR1) from Arabidopsis thaliana. However, (+)-valencene was predominantly oxidized to β-nootkatol and only minor amounts of (+)-nootkatone (9.66 mg/L) were produced. We further tackled the oxidation of β-nootkatol to (+)-nootkatone by screening various dehydrogenases. Our results showed that the short-chain dehydrogenase/reductase (SDR) superfamily dehydrogenases ZSD1 of Zingiber zerumbet and ABA2 of Citrus sinensis were capable of effectively catalyzing β-nootkatol oxidation to (+)-nootkatone. The yield of (+)-nootkatone increased to 59.78 mg/L and 53.48 mg/L by additional overexpression of ZSD1 and ABA2, respectively. CONCLUSION:We successfully constructed the (+)-nootaktone biosynthesis pathway in S. cerevisiae by overexpressing the (+)-valencene synthase CnVS, cytochrome P450 monooxygenase HPO, and SDR family dehydrogenases combined with the MVA pathway engineering, providing a solid basis for the whole-cell production of (+)-nootkatone. The two effective SDR family dehydrogenases tested in this study will serve as valuable enzymatic tools in further optimizing (+)-nootkatone production.

Dataset Information

MRX8, the conserved mitochondrial YihA GTPase family member, is required for de novo Cox1 synthesis at suboptimal temperatures in Saccharomyces cerevisiae.

Publications

<i>MRX8</i>, the conserved mitochondrial YihA GTPase family member, is required for de novo Cox1 synthesis at suboptimal temperatures in <i>Saccharomyces cerevisiae</i>.

Similar Datasets

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